The proposed study will investigate the incidence and pattern of breast-milk jaundice in two groups of breast-fed infants. Additionally, the relationship of breast-milk jaundice to exaggerated physiologic jaundice in breast-fed infants will be examine. The proposed study will attempt to answer the following questions: 1. Is the incidence of breast-milk jaundice greater than that currently reported in the literature? 2. Is the incidence of breast-milk jaundice greater in infants with exaggerated physiologic jaundice? 3. Does the onset, peak, severity, and duration of breast-milk jaundice differ from that of exaggerated physiologic jaundice in the newborn? This study represents the first in a series on jaundice in the breast-fed infant and will provide information from which practioners can base their counseling and interventions regarding this syndrome. Infants in Group I have no evidence of hyperbilirubinemia. Infants in Group II include those infants who developed exaggerated physiologic jaundice. The study population will include only normal full term infants with uncomplicated prenatal and intrapartum courses. Infants in both groups will be screened on days 2,3,5,7,9,11, and 13 following birth using the Minolta/Air Shields Jaundice Meter 101, a non-invasive bilirubin screening device. Any infant whose screen on day 13 indicates a level greater than 10 mgm/dl will be followed every other day until the jaundice meter indicates a level below 10 mgm/dl. The total number of infants in Group I and in Group II who have jaundice identified as breast-milk jaundice will be reported as a percentages. A one-sample test of the departure of the overall observed percentage from the 2% reported rate in the literature will be performed to test whether the incidence of breast-milk jaundice is greater than the rate reported in the literature. The incidence of identified breast-milk jaundice in Groups I and II will be compared using the two-sample test of independent proportions. The onset, peak, and decline of each type of jaundice will be graphically illustrated and described using appropriate summary statistics. Two-way analysis of variance will repeated measures will be applied to examine trends in bilirubin levels over time between those with identified breast-milk jaundice and those with exaggerated physiologic jaundice.